From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Torsional deflection and polar moment of inertia experiments for the Phantom crankshaft.
| Identifier | ExFiles\Box 25\3\ Scan157 | |
| Date | 4th November 1926 guessed | |
| COPY. PHANTOM - CRANKSHAFT VIBRATIONS. In connection with the Phantom crankshaft vibrations experiments, we have taken a torsional deflection curve of this crankshaft supported in its bearings in the crankcase. For this purpose the flywheel was locked and a torque applied at the front end through an arm bolted to the spring drive hub. The torque arm was long - 4 ft. - to reduce to a minimum the downward thrust from the applied load. The actual deflection readings were made by a reflected beam of light on to a scale from two small mirrors attached to each end of the crankshaft. This method gives a high degree of accuracy and prevents errors due to any flexibility or slip of holding or twisting parts. A curve is appended giving the torque-deflection of the standard Phantom crankshaft between flywheel and spring drive hub when supported in its bearings. From the curve the torsional rigidity is 43500 lbs.ft. per radian of twist or 2.68 times stiffer than the 20 HP. We next determined the polar moments of inertia of all the crankshaft parts by the usual two-wire suspension method: We obtained the following results :- | PART. | (lbs.) WEIGHT. | POLAR MOMENT OF INERTIA. (W/g K^2) | |--------------------------------------------------------------|----------------|------------------------------------| | Crankshaft - complete. | 75.875 | .06738 units. | | Big end of conn. rod (2.64 lbs. each rod - to tal for six). | 15.84 | .02579 " | | Spring drive parts. | 14.125 | .01437 " | | Flywheel complete with clutch. | 168.25 | 1.384 " | The spring drive parts do not include the slipper wheels because being free to slip, they do not add to the polar inertia in this case. The equivalent rotating weight of the conn. rods was found approximately by weighing the big ends while supporting the other end horizontally and they were of the loose shell type. contd :- | ||